1. Field of the Invention
The present invention generally concerns tooling and equipment utilized in the maintenance and servicing of oil and gas production wells, and more particularly relates to a power tong of the type utilized in conjunction with back-up tongs or wrenches to make or break threaded joints between successive tubing elements that extending through a well bore into underground deposits.
2. Related Art
In drilling for oil and gas, it is necessary to assemble a suing of drill pipe joints. Thus, a tubular drill string may be formed from a series of connected lengths of drill pipe and suspended by an overhead derrick. These lengths of drill pipe are connected by tapered external threads (the pin) on one end of the pipe, and tapered internal threads (the box) on the other end of the pipe.
During the drilling and completion of a well, as the well is drilled deeper, additional joints of pipe are periodically added to the drill string and, as the drill bit at the end of the drill string is worn, the drill string must occasionally be pulled from the well and reinstalled for maintenance purposes. The process of pulling or installing the drill string is referred to as “tripping.” During tripping, the threaded connections between the lengths of drill pipe are connected and disconnected as needed. The connecting and disconnecting of adjacent sections of drill pipe (referred to as making or breaking the connection, respectively), involves applying torque to the connection and rotating one of the pipes relative to the other to fully engage or disengage the threads.
In modern wells, a drill string may be thousands of feet long and typically is formed from individual thirty-foot sections of drill pipe. Even if only every third connection is broken, as is common, hundreds of connections have to be made and broken during tripping. Thus, the tripping process is one of the most time consuming and labor intensive operations performed on the drilling rig.
Currently, there are a number of devices utilized to speed tripping operations by automating or mechanizing the process of making and breaking a threaded pipe connection. These devices include tools known as power tongs, iron roughnecks, and pipe spinners. Many of these devices are complex pieces of machinery that require two or more people to operate and require multiple steps, either automated or manual, to perform the desired operations. Additionally, many of these devices grip the pipe with teeth that can damage the drill pipe and often cannot be adjusted to different pipe diameters without first replacing certain pieces, or performing complex adjustment procedures.
In particular, roughnecks combine a torque wrench and a spinning wrench, simply called a spinner, to connect and disconnect drill pipe joints of the drill string. In most instances, the spinner and the torque wrench are both mounted together on a carriage. To make or break a threaded connection between adjoining joints of drill pipe, certain roughnecks have a torque wrench with two jaw levels. In these devices, an upper jaw of the torque wrench is utilized to clamp onto a portion of an upper tubular, and a lower jaw clamps onto a portion of a lower tubular (e.g., upper and lower threadedly connected pieces of drill pipe). After clamping onto the tubular, the upper and lower jaws are turned relative to each other to break or make a connection between the upper and lower tubulars. A spinner, mounted on the carriage above the torque wrench, engages the upper tubular and spins it until it is disconnected from the lower tubular (or in a connection operation, spins two tubulars together prior to final make-up by the torque wrench).
Generally, a spinner comprises four rollers, each driven by a separate hydraulic motor, that engage the outer wall of the drill pipe to spin the pipe. However, other spinners exists that use flexible belts or chains to engage and spin the pipe. An example of a chain spinner is the SPINMASTER® spinner made available from Hawk Industries. The basic function and construction of the SPINMASTER® spinner are disclosed in U.S. Pat. No. 4,843,924 (Hauk).
In particular, the Hauk '924 patent discloses a spinner that includes first and second elongate casing sections that are pivotally connected to each other at a pivot, and first and second driven sprockets mounted, respectively, on the casing sections at locations remote from the pivot. The spinner also includes a drive sprocket, mounted on the first casing section, driven by a motor-gear assembly and a continuous chain mounted around the drive sprocket, and around the first and second driven sprockets. The chain has an inverse internal portion adapted to receive and directly contact a tubular well element to be rotated. Cylinders connected between the casing sections pivot them toward and away from each other and thus, alternately clamp the inverse internal portion around the well element, and release such element from the inverse internal portion of the chain.
Some prior art spinners, such as the SPINMASTER®, are also adjustable to accommodate pipes of varying diameter. These spinners are adjusted by changing the location of the drive sprocket relative to the driven sprockets, thus the effective length of the chain is adjusted to accommodate different pipe diameters. While adjustable spinners are versatile, these spinners must be manually adjusted by the operator during use. In many instances, the operator must climb atop of the spinner, disengage fasteners or locking pins holding the drive sprocket in place, manually adjust the drive sprocket to a desired location, and re-fasten or lock the drive sprocket at its new location. Manually adjusting the spinner can therefore be consuming and dangerous.
Thus, a need exists for an automated spinner that allows the operator to change the pipe size of the spinner from a remote location to provide a safer and quicker pipe change.